oj.uz

Submission #245374

# Submission time Handle Problem Language Result Execution time Memory
245374 2020-07-06T07:31:45 Z lyc Potemkin cycle (CEOI15_indcyc) C++14
40 / 100
 478 ms 2560 KB 
#include <bits/stdc++.h>
using namespace std;

#define TRACE(x) cerr << #x << " :: " << x << endl
#define _ << " " <<
#define SZ(x) (int)(x).size()
#define ALL(x) (x).begin(),(x).end()
#define FOR(i,a,b) for(int i=(a);i<=(b);++i)
#define RFOR(i,a,b) for (int i=(a);i>=(b);--i)
using ii = pair<int,int>;

const int mxN = 1e3+5;
const int mxR = 1e5+5;

int N, R;
vector<int> al[mxN];
bool am[mxN][mxN];

bool block[mxN];
vector<int> ans;

struct UFDS {
    int p[mxN], s[mxN];
    UFDS() { FOR(i,1,N) p[i] = i, s[i] = 1; }
    int finds(int i) { return (p[i] == i) ? i : (p[i] = finds(p[i])); }
    bool sames(int i, int j) { return finds(i) == finds(j); }
    bool unions(int i, int j) {
        int x = finds(i), y = finds(j);
        if (x == y) return 0;
        if (s[x] < s[y]) swap(x,y);
        p[y] = x, s[x] += s[y];
        return 1;
    }
};

int dist[mxN], pa[mxN];
queue<int> q;

void bfs(int s, int t) {
    memset(dist,-1,sizeof dist);
    memset(pa,-1,sizeof pa);
    dist[s] = 0; q.push(s);
    while (!q.empty()) {
        int u = q.front(); q.pop();
        if (u == t) return;
        for (int v : al[u]) if (!block[v]) {
            if (dist[v] == -1) {
                dist[v] = dist[u]+1;
                pa[v] = u;
                q.push(v);
            }
        }
    }
    return;
}

bool solve(int s) {
    block[s] = 1;
    for (int v : al[s]) block[v] = 1;

    UFDS uf;
    FOR(u,1,N) for (int v : al[u]) if (!block[u] || !block[v]) {
        uf.unions(u,v);
    }

    FOR(i,0,SZ(al[s])-1){
        int u = al[s][i];
        FOR(j,i+1,SZ(al[s])-1){
            int v = al[s][j];
            if (!am[u][v] && uf.sames(u,v)) {
                block[u] = block[v] = 0;
                bfs(u,v);
                for (int x = v; x != -1; x = pa[x]) ans.push_back(x);
                ans.push_back(s);
                return true;
            }
        }
    }

    block[s] = 0;
    for (int v : al[s]) block[v] = 0;
    return false;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    cin >> N >> R;
    FOR(i,1,R){
        int A, B; cin >> A >> B;
        al[A].push_back(B);
        al[B].push_back(A);
        am[A][B] = am[B][A] = 1;
    }

    FOR(i,1,N){
        if (solve(i)) {
            for (int x : ans) {
                cout << x << ' ';
            }
            cout << '\n';
            return 0;
        }
    }
    cout << "no" << '\n';
}

Subtask #1
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 384 KB Output is correct
2 Correct 5 ms 384 KB Output is correct
3 Correct 6 ms 384 KB Output is correct
4 Correct 5 ms 384 KB Output is correct
5 Correct 5 ms 384 KB Output is correct

Subtask #2
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 384 KB Output is correct

Subtask #3
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 384 KB Output is correct
2 Incorrect 5 ms 384 KB Wrong answer on graph without induced cycle

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 496 KB Output is correct

Subtask #5
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 512 KB Output is correct
2 Incorrect 5 ms 512 KB Wrong answer on graph without induced cycle

Subtask #6
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 14 ms 768 KB Output is correct
2 Correct 6 ms 768 KB Output is correct
3 Correct 6 ms 768 KB Too short sequence
4 Incorrect 6 ms 768 KB Wrong answer on graph without induced cycle

Subtask #7
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 6 ms 768 KB Too short sequence
2 Incorrect 5 ms 768 KB Wrong answer on graph without induced cycle

Subtask #8
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 21 ms 2304 KB Too short sequence
2 Correct 11 ms 1792 KB Too short sequence
3 Correct 478 ms 2304 KB Output is correct
4 Correct 202 ms 1912 KB Output is correct

Subtask #9
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 12 ms 1792 KB Too short sequence
2 Incorrect 10 ms 1792 KB Wrong answer on graph without induced cycle

Subtask #10
0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 35 ms 2552 KB Output is correct
2 Correct 163 ms 2432 KB Output is correct
3 Correct 20 ms 2560 KB Too short sequence
4 Incorrect 18 ms 2560 KB Wrong answer on graph without induced cycle